Zip lines are thrill-ride systems which are predominantly used for amusement-type operations. A common zip line system includes a suspended cable (constructed of aluminum, steel or similar metallic material) stretched between, and rigidly affixed to, separate supporting structures. One end of the suspended cable is affixed to a support structure which is located at an elevation higher than that of the opposite end. The result is a downward slope of the suspended cable. The higher end of the suspended cable is referred to as the beginning, and the lower end is referred to as the end. A common zip line trolley consists of either one or two pulleys affixed to a common housing. The pulleys of the trolley are placed on top of the suspended cable and a rider holds on to, or is tethered to, the trolley via a conventional safety harness. The downward slope of the suspended cable facilitates a gravitational force which propels the trolley and rider along the suspended cable.
Zip lines are used by individuals at theft own personal locations as well as by businesses in commercial applications. Many commercial zip line canopy tours employ the use of multiple suspended cables allowing for a variety of rides for patrons. Common trolleys are most often constructed of steel, or similar rigid material. Unfortunately, they do not afford a rider the ability to control his or her speed of descent while traversing along the suspended cable. Devices and systems similar to zip lines are witnessed within the oil industry relating to lowering endangered personnel from oil derrick towers.
Various types of braking systems for common zip lines are known within the art. The most common methods of zip line braking systems presently available include gravity braking, impact braking and frictional braking. None of the braking systems presently available, for common zip lines allow a rider control of his or her speed in a safe, economical and easy-to-use manner.
A gravity braking method relies on the natural sag in the suspended cable coupled with the rider's weight to bring he or she to a stop. The ride ends at a point where the rider's momentum ceases to propel the rider along the suspended cable. These designs do not always permit the user to end at the preferred destination and may require further repositioning of the user or moving a ladder or walkway to the user's ending position.
Impact braking methods commonly utilize an elastic cord (often a bungee cord or other similar material) along with a small block. The block is affixed close to the ending-end and in a manner such that it can slide freely along the suspended cable. One end of the bungee cord is fastened to the block and the other end is rigidly affixed to a point on the ground. When a rider traversing along the suspended cable makes contact with the block, the bungee cord expands and brings the rider to a stop. In addition to elastic cords, rubber tires affixed to the ending-end of a suspended cable are often used as an impact braking method. Rubber tires witness similar results and potential safety hazards as those experienced with elastic cords. Further, impact braking is known to cause the rider to swing, sometimes in a violent and rapid manner.
Regarding frictional braking, one form requires the rider to wear a glove. While traversing along the suspended cable, the rider squeezes the suspended cable with the hand wearing the glove. This creates dynamic friction along the suspended cable, thus slowing the rider. This can be dangerous in that the rider can wear a hole through the glove and rub his or her skin along the suspended cable. Another form of frictional braking requires the rider to drag his or her feet along the ground while approaching the ending-end. Both of these methods are unpredictable and produce unacceptable results.
Other braking methods known within the art add considerable expense and complexity to a common zip line. Many are rigidly fixed to a particular suspended cable or a particular trolley, thus not easily transportable among other suspended cables. They often include a complicated series of additional pulleys and cables which all must work in unison to be operational. Should any one piece of such a braking system malfunction, the entire braking mechanism and rider's safety can be jeopardized.
Further, some other braking methods force the rider to face down the cable (i.e. towards the end of the run). While this may be desirable in some applications, some riders may desire to face sideways or even backwards for a different experience while traversing from the beginning to end.